Overloading and overriding

Question

What is the difference between overloading and overriding

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Overloading  Overloading is when you have multiple methods in the same scope  with the same name but  different signatures      Overloading public class test       public void getStuff int id             public void getStuff string name             Overriding  Overriding is a principle that allows you to change the functionality of a method in a child class      Overriding public class test           public virtual void getStuff int id                          Get stuff default location              public class test2   test           public override void getStuff int id                          base getStuff id                 or - Get stuff new location

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Overloading is a part of static polymorphism and is used to implement different method with same name but different signatures  Overriding is used to complete the incomplete method  In my opinion there is no comparison between these two concepts  the only thing is similar is that both come with the same vocabulary that is over

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Having more than one methods constructors with same name but different parameters is called overloading  This is a compile time event   Class Addition       int add int a  int b             return a b          int add int a  int b  int c            return a b c           public static main  String   args             Addition addNum   new Addition         System out println addNum add 1 2         System out println addNum add 1 2 3             O p   3 6   Overriding is a run time event  meaning based on your code the output changes at run time   class Car       public int topSpeed                  return 200          class Ferrari extends Car       public int topSpeed                 return 400            public static void main String args                  Car car   new Ferrari            int num  car topSpeed            System out println  Top speed for this car is    num             Notice there is a common method in both classes topSpeed    Since we instantiated a Ferrari  we get a different result   O p   Top speed for this car is  400

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Overloading is the concept in which you have same signatures or methods with same name but different parameters and overriding  we have same name methods with different parameters also have inheritance is known as overriding

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As Michael said    Overloading   Multiple method signatures  same method name Overriding   Same method signature  declared virtual   implemented in sub classes   and   Shadowing   If treated as DerivedClass it used derived method  if as BaseClass it uses base method

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in C  there is no Java like hidden override  without keyword override on overriding method  see these C  implementations   variant 1 without override    result is 200             class Car           public int topSpeed                 return 200                       class Ferrari   Car           public int topSpeed                    return 400                       static void Main string   args           Car car   new Ferrari            int num  car topSpeed            Console WriteLine  Top speed for this car is    num           Console ReadLine            variant 2 with override keyword  result is 400      class Car           public virtual int topSpeed                 return 200                       class Ferrari   Car           public override int topSpeed                    return 400                       static void Main string   args           Car car   new Ferrari            int num  car topSpeed            Console WriteLine  Top speed for this car is    num           Console ReadLine            keyword virtual on Car class is opposite for final on Java  means not final  you can override  or implement if Car was abstract

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Overloading   Multiple method signatures  same method name Overriding   Same method signature  declared virtual   implemented in sub classes   An astute interviewer would have followed up with   What s the difference between overriding and shadowing

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Method overloading and Method overriding are 2 different concepts completely different  Method overloading is having the same method name but with different signatures  Method overriding is changing the default implementation of base class method in the derived class  Below you can find 2 excellent video tutorials explaining these concepts   Method overriding Vs hiding   Method overloading

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Simple definitions for overloading and overriding  Overloading  Compile Time Polymorphism    Functions with same name and different parameters   public class A       public void print int x  int y                Console WriteLine  Parent Method             public class B   A       public void child                 Console WriteLine  Child Method               public void print float x  float y                Console WriteLine  Overload child method              Overriding  Run Time Polymorphism     Functions in the extended class with same name and same parameters as in the base class  but with different behaviors   public class A       public virtual void print                 Console WriteLine  Parent Method             public class B   A       public void child                 Console WriteLine  Child Method               public override void print                 Console WriteLine  Overriding child method

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I want to share an example which made a lot sense to me when I was learning   This is just an example which does not include the virtual method or the base class  Just to give a hint regarding the main idea   Let s say there is a Vehicle washing machine and it has a function called as  Wash  and accepts Car as a type    Gets the Car input and washes the Car   public void Wash Car anyCar            wash the car     Let s overload Wash   function  Overloading   public void Wash Truck anyTruck        wash the Truck       Wash function was only washing a Car before  but now its overloaded to wash a Truck as well     If the provided input object is a Car  it will execute Wash Car anyCar  If the provided input object is a Truck  then it will execute Wash Truck anyTruck    Let s override Wash   function  Overriding   public override void Wash Car anyCar        check if the car has already cleaned    if anyCar Clean             wax the car         else           wash the car          dry the car          wax the car               Wash function now has a condition to check if the Car is already clean and not need to be washed again     If the Car is clean  then just wax it   If not clean  then first wash the car  then dry it and then wax it       So the functionality has been overridden by adding a new functionality or do something totally different

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shadowing   maintains two definitions at derived class and in order to project the base class definition it shadowes hides derived class definition and vice versa

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Another point to add   Overloading More than one method with Same name  Same or different return type  Different no of parameters or Different type of parameters  In Same Class or Derived class   int Add int num1  int num2  int Add int num1  int num2  int num3  double Add int num1  int num2  double Add double num1  double num2   Can be possible in same class or derived class  Generally prefers in same class  E g  Console WriteLine   has 19 overloaded methods   Can overload class constructors  methods   Can consider as Compile Time  static   Early Binding  polymorphism                                                                                                          Overriding cannot be possible in same class   Can Override class methods  properties  indexers  events   Has some limitations like  The overridden base method must be virtual  abstract  or override  You cannot use the new  static  or virtual modifiers to modify an override method   Can Consider as Run Time  Dynamic   Late Binding  polymorphism   Helps in versioning http   msdn microsoft com en-us library 6fawty39 aspx                                                                                                         Helpful Links  http   msdn microsoft com en-us library ms173152 aspx Compile time polymorphism vs  run time polymorphism

[c#] Overloading and overriding

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